This invention relates generally to television receiving apparatus and, more particularly, is directed to a television receiving apparatus for reproducing a sound broadcast in two languages.
In many cases, it is desirable to produce a television broadcast in different languages. This is particularly important in a country in which, for example, two languages are spoken. For example, in a country in which English and Spanish are spoken, it may be desirable to reproduce a television broadcast of a football game in either the English language or the Spanish language.
In accordance with one proposed system, a television receiver is provided for reproducing stereo sound in a first language and monaural sound in a second language in a two language broadcast. In such case, the transmitted television signal includes a multiplexed sound broadcast signal comprised of a main sound signal formed by the sum of a left channel sound signal and right channel sound signal in the first language, for example, the English language, a second sound sub-signal formed by the difference of the left channel sound signal and right channel sound signal in the English language and a third monaural sound signal in a second language, for example, in the Spanish language. A matrix circuit is provided for combining the sum signal and difference signal in the English language to provide the left channel sound signal and right channel sound signal at respective outputs thereof as a stereo sound signal in the English language. The third sound signal is independently separated from the multiplexed sound broadcast signal and supplied to an output as a monaural sound signal in the second language.
However, with such proposed system, an FM demodulation circuit is provided in a first path for producing the difference signal in response to the multiplexed sound broadcast signal and which is supplied to the matrix circuit, and a second FM demodulation circuit is provided in still another path for producing the third sound signal in response to the multiplexed sound broadcast signal. The use of two FM demodulation circuits, however, is relatively inefficient, complex and expensive.